This invention has its origin in problems associated with mounting and dismounting of cutting inserts for milling tools, in particular when these are numerous. Mostly, the cutting inserts for milling tools are indexable by being formed with a plurality of alternately individually usable cutting edges. Particularly usual milling cutting inserts are single-sided and have four alternately usable cutting edges, as well as a central hole, which mouths in a chip face and is intended for a screw by means of which the cutting insert can be fixed in an appurtenant seat in the basic body. In most cases, such cutting inserts are radially mounted, i.e., have their principal planes facing forward in the direction of rotation of the basic body, or, in other words, have their principal planes radially oriented in relation to the milling cutter body.
The work to either replace entirely worn out cutting inserts or to index up fresh cutting edges is time-consuming and at times cumbersome because the fixing screw for each cutting insert has to either be entirely unscrewed to allow removal of the cutting insert from the seat, or at least be untightened somewhat to allow turning of the cutting insert into a new index position in the seat. Not rarely, the cutting inserts are placed in chip channels of limited volume, and thereby difficult to access for a key for the screw. It should here be mentioned that large milling tools, such as face mills having a diameter of 500 mm or more, may include scores of indexable cutting inserts, which have to be loosened one by one upon indexing as well as replacement.
By U.S. Pat. No. 4,541,165, a device intended for milling tools is known, which makes use of mechanical means for on one hand clamping an indexable cutting insert in an operative state, and on the other hand—if required—providing for a contact free indexing of the cutting insert. In the document, a milling cutter is disclosed, the basic body of which on its outside is equipped with a plurality of tangentially spaced-apart cutting inserts, each one of which interacts with a cutting edge replacement device. More precisely, the cutting insert is arranged on a (tangentially) front end of a slide element, the rear end of which is articulately connected with a lever, which protrudes radially from the envelope surface of the basic body to be able to be actuated by an activatable, if required, impact member. In its operative state, the cutting insert is kept in place by means of a mechanical spring, which is kept pressed against the chip face of the cutting insert.
For several reasons, the milling tool and its cutting edge replacement devices disclosed in U.S. Pat. No. 4,541,165 are not very suitable for practical milling. One of these reasons is that said levers protrude radially from the periphery of the basic body. Another is that the spring clamping the cutting insert is open exposed to hammering, hot chips. A particularly aggravating disadvantage is, however, that the cutting inserts only can be indexed or replaced one by one. Even if the screws clamping the cutting inserts do not need to be loosened manually in connection with indexing, the indexing work is still time-consuming because the cutting edge exchange mechanisms for all cutting inserts have to—by stepwise turning up of the basic body—be brought into positions in which the individual levers contact and can be actuated by the impact member. In addition, replacement of worn out cutting inserts will probably be cumbersome and time-consuming because the clamping springs have to be removed before the cutting inserts can be picked away.